Write Movar's copy

docs/copy.md is the authority — nine sections covering voice, the two sides, UA and EN mechanics, register, lexicon, and the nevers. Read the sections that bear on your edit before writing. This skill is the operating procedure around it, not a summary of it.

Where the strings live

Surface	File
Extension UI — popup, options, curtains, errors	packages/i18n/src/messages-{uk,en}.ts
Content-script strings	apps/extension/src/lib/i18n/content-strings-{en,uk}.ts
Marketing site (all pages, OG, deep dives)	apps/marketing/src/i18n.ts
Safari host app	apps/safari-host-app/src/i18n/messages-{uk,en}.ts
Store listings, release notes	apps/extension/store-assets/**, RELEASE-NOTES.md

The four things that actually go wrong

1. One locale ships without the other

UA and EN are both canonical. A new string needs both in the same change — and they are drafted in parallel, not translated (docs/copy.md preamble). UA sets the register when one has to land first.

2. The UA reads like a translation

This is the failure mode a machine reaches for by default. docs/copy.md §4.10–4.14 is the checklist; the tests that catch the most:

• Token-for-token alignment with the EN sibling is the tell. The shipped pair "Got it." — then shows Russian anyway / «Прийнято.» — і показує російською drops anyway in UA because the dash already carries it.
• «дозволяє вам», «допомагає вам», «забезпечує» — direct renderings of allows you to / helps you / provides. Say what happens instead.
• Active participles: «фільтруючий», «блокуючий» → «фільтр», «який блокує».
• Канцелярит: «здійснювати перевірку» → «перевіряти».
• AI register tells: triads, «не просто X, а Y» as a default sentence shape, «У світі, де…», suspiciously even bullet lists.

Mechanics that have no lint rule and are therefore review-only: « » guillemets (§4.2), the ʼ apostrophe at U+02BC (§4.3), em-dash with spaces (§4.4).

3. The copy claims something the product does not do

Every user-facing claim must be literally true against the code, because store reviewers read these surfaces. Verify against the source, not against another copy surface — mirrored copy propagates a wrong claim rather than catching it. Recent examples of claims that were false when written:

• «список сайтів, який ми постійно розширюємо» — there is no list; @movar/lang-pickers walks the DOM for any switcher.
• Per-element filtering implied to work on marketplaces — models is [googleModel, youtubeModel] and nothing else.
• «Знімки з реальної збірки — не макет» on the homepage drum — the PNGs are Storybook-rendered approximations with fictitious .example domains, which apps/extension/store-assets/REQUIREMENTS.md in fact requires.

Before shipping a capability claim, grep for the behaviour and read it.

4. The claim is true here and stale in six other places

Product claims are mirrored across surfaces with no guard. Changing a feature or a permission means reconciling every copy of its claim: both privacy.astro pages, both store PRIVACY-FORMs, STORE-LISTING.md, docs/copy.md, README.md, the deployment checklist, and the Edge asset notes. Grep the distinctive phrase across the repo before you consider an edit done.

Procedure

1. Read the relevant docs/copy.md sections — always §1 (voice) and §7.4 (forbidden lexicon); §4 for UA, §5 for EN, §6 for length caps.
2. Draft both locales. UA first unless the string is EN-native by nature.
3. Verify the claim against code, not against another string.
4. Run the §4.10–4.14 pass over the UA — read it aloud; if it maps word for word onto the EN, rewrite it.
5. Sweep for mirrors of any claim you changed.
6. Check — pnpm --filter @movar/marketing typecheck, and pnpm check:readme when the hero tagline or a product promise moved. Marketing copy changes invalidate the e2e visual baselines; regenerate on a quiet machine (pnpm e2e:baselines:marketing).

When copy.md and the corpus disagree

The corpus wins, and the doc gets corrected in the same change — §4 is explicitly descriptive of the current corpus. Three rules were found stale this way and fixed rather than obeyed: a claimed ESLint apostrophe rule that does not exist, a string path that had moved to packages/i18n, and a ban on «Мовар» that 160 shipped strings ignore. Do not "fix" working copy to satisfy a stale rule.